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Ceramic Tile

The tile industry is the largest sector of the ceramic industry. Tile production is done at a wide range of temperatures using all manner of body and glaze types and process methods. While some countries use little ceramic tile, others cover every surface of buildings, even sidewalks with tile. The quality of tile a company produces is a real testament to the expertise of their technical staff, this is because the engineering challenges in tile production are daunting indeed!

Wall and floor tile make up the largest portion of production. Floor tile must be durable, non slip, dense, strong, easily cleaned, very flat. Wall tile does not have to be any of these, although of course, many types would benefit having one or more of these properties, density especially.

Tile can be formed using many techniques. Hand rolling is surprisingly common in traditional techniques. Tile can be extruded and wet pressed, but by far the most common is dust pressing. Giant hydraulic machines are used to press moist powder (at 500kg/cm2) into flats that can be larger than a meter square! Since shrinkage is almost zero no warpage occurs during drying. Glaze can be applied to the dry tile. Firing is done in roller kilns that heat so evenly top and bottom that little or no warping occurs (despite significant firing shrinkage). Not only this, tiles move thru the kiln quickly. This ability to quickly fire such large flat shapes planar is perhaps the greatest achievement in kiln firing technology.

Huge quantities of unglazed porcelain tile are produced. Planarity is a big problem (because porcelain shrinks a lot on firing), so much so that tile have to be ground flat after firing. That alone is an entire industry.

Much tile is covered with a white engobe before glazing. This makes it possible to employ a local clay that fires buff, brown or even red yet have a porcelain-like surface on which to apply glaze. Technicians expend much effort to match firing shrinkage and COE to the body and control slurry properties to get even coverage and good dry bonding.

It would seem that tile needs to be vitreous to be strong and resistant to liquid penetration and crazing but this is not the case. Well fitted engobes and glazes can make it possible to use non-vitrifying bodies of surprisingly high porosity to produce tile of very good quality. Such bodies are easier to fire flat because they shrink less.

The tile industry is at the leading edge of decoration technology. Of course there are many traditional methods of decoration, but today there are just three important words: Ink jet printing. Manufacturers can make a tile look like marble by simply printing a picture of marble on it! Photo realism is possible. Print heads are as wide as the fast moving tiles passing under them and there are separate heads for each color. Entire industries have formed around every aspect of printing (design, ink chemistry, ink rheology, nano particle pigments, machine design).

Technicians fight a constant battle against pinholes. Just one can ruin a tile. Companies must go to incredible lengths in material processing, recipe development and production parameter control to create a pinhole-free tile. They also struggle to keep the tiles flat through drying and firing. Matching glaze and engobe thermal expansion to the body is very important in keeping tiles flat.

Huge supply industries have grown to provide tile manufacturers with everything they need. Cutting edge technology characterizes the equipment industry especially. And, as noted, decorating. Suppliers are constantly developing new lines of glazes and novel surface treatments. There are even companies that do nothing but build tile factories, complete and ready to move in and switch on. And, of course, material suppliers (e.g. frits, feldspar, silica, talc, clays, pigments). Suppliers provide enough tech support and expertise that tile manufacturers can even outsource much of their engineering needs.

Making ceramic tile shapes by 3D printing your own cookie cutters

Making ceramic tile shapes by 3D printing your own cookie cutters

This was done on an affordable RepRap printer. The red plastic templates were drawn in Illustrator, extruded in Fusion 360 and sliced and printed using Simplify3D (which took about 30 minutes each). The round wooden block was used to press these cookie-cutters into the clay. The plastic wrap made sticking a non issue (and rounds the corners nicely). The clay is a low fire, buff burning talc body (Plainsman L212). Commercial bottled glazes were applied by brushing (in three coats) after bisque. The tiles were fired at cone 03. This is an old classic design that I discovered when researching Damascus tile. The toughest obstacle was learning how to use Fusion 360. It turns out that cookie cutters are a starter project for many 3D software packages, there are lots of videos on making them.

Out Bound Links

By Tony Hansen

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